Congratulations to Gunnar Eriksson on the 50 years anniversary of his publication on SOLGAS

In Acta Chemica Scandinavica Gunnar Eriksson published a series of publications which culminated in 1971 in the third paper titled

SOLGAS, a Computer Program for Calculating the Composition and Heat Condition of an Equilibrium Mixture. [1]

In the abstract he stated: “A computer program named SOLGAS is described. SOLGAS is a program for calculating equilibrium compositions and heat conditions in systems containing ideal gaseous species and pure condensed phases. The method of the equilibrium calculations is based upon minimization of the free energy of the system considered.”

The section “Comments on the program SOLGAS”, starts with an offer: “SOLGAS (…) can be requested from the author”, but obviously he was not able to share his program via Github or alike. He had to use punch cards [2] and therefore offered to share SOLGAS “together with a punching guide”. Aachen was the place-to-be both in terms of thermochemistry (ever heard of Barin-Knacke-Kubaschewski’s books) and the computational thermochemistry group surrounding Philip Spencer and Klaus Hack was able to convince Gunnar to move to Germany. He had in his luggage a computer program called SOLGASMIX [3], meanwhile on computer tape. What followed is history: First SOLGASALLOY [4], then ChemSage [5] and since 2001 FactSage [6] – they all rely internally on the nucleus that was named 50 years ago SOLGAS.

The “Fact” in FactSage stands for Facility for the Analysis of Chemical Thermodynamics which was a joint research project between École Polytechnique and McGill University, Montreal Canada ( You might like to know what “Sage” stands for?

It is the SOLGASMIX-based advanced Gibbs energy minimizer.

But for us, it will always be SOLGASMIX av Gunnar Eriksson.


Congratulations and thank you, Gunnar!



[3]: Eriksson, G. and Rosen, E. Thermodynamic studies of high-temperature equilibriums. VIII. General equations for the calculation of equilibriums in multiphase systems. Chemica Scripta (1973), 4, 193.




Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.